Association of Race and Change in Ankle-Brachial Index: The Atherosclerosis Risk in Communities (ARIC) Cohort

Objective: This study evaluates the association of self-reported race with change in ankle-brachial index (ABI) over time and modification of this association by paraoxonase gene (PON1, PON2 and PON3) single nucleotide polymorphisms (SNPs). Methods: This longitudinal study included 11,992 (N = 2952 Black, N = 9040 White) participants from the Atherosclerosis Risk in Communities (ARIC) cohort with PON genotyping. Mixed-effects models examined whether race was associated with change in ABI over time after adjustment for known peripheral artery disease (PAD) risk factors. Results: Change in ABI over time differed between Whites and Blacks (race-time interaction, p < 0.0001). Stratified analyses showed that ABI values were better in both Blacks and Whites who completed high school or more education compared to those who completed less education. None of the PON SNPs met the significance level (p < 0.001) after Bonferroni correction for multiple comparisons. Conclusions: ABI differences by race were small and although statistically significant, may not be clinically significant. Change in ABI over time varies by race and may be modified by education. Results suggest that higher education may influence the lifestyle and behavioral choices contributing to better ABI in both Blacks and Whites. Further studies are needed to confirm this observation.